The goal of this fellowship is to ascertain the role of the Lim- l gene product in Drosophila head and nervous system development. The objectives in doing so are, to define the specific role Lim-l has in these processes, advance the current knowledge of head and nervous system development, and identify parallels to the vertebrate Lim- l gene. The specific aims are designed to concisely address each of these issues. Specific aim #1 will examine the temporal and spatial relationship of Drosophila Lim-l with respect to relevant developmental regulators. By immunostaining for Lim-l in wild-type and mutant Drosophila embryos, the genetic and molecular position of Lim-l can be determined and placed in an appropriate hierarchy. Specific aim #2 will entail the molecular and genetic mapping of the Lim- l locus, and the generation of a loss-of-function mutations by genetic and PCR screens. Specific aim #3 will address the consequent phenotype of the Lim-l mutations. The analysis will focus on defining the molecular and morphological phenotypes observed in head formation and nervous system development. This will be done by staining for pertinent markers and analyzing cuticle structures of the Lim-l mutant embryos. These studies will reveal new and important information about how the LIM class transcription factor, Lim-l functions in Drosophila development, and will provide a clearer understanding of the similarities that exist between Drosophila and vertebrates.